A technique of video coding is known as a technique used in an apparatus, such as a television, a personal computer (PC), a cellular phone or the like, which displays image signals, with the goal of coding a video signal at a low bit rate for transmission. For example, Moving Picture Experts Group (MPEG), which is a set of international standards for compression of video signals, defines formats for compressing and coding video signals, using entropy coding, by creating predicted images and obtaining information regarding creation of such predicted images as well as information regarding orthogonal transformation and quantization of difference information between the predicted images and images to be coded. These MPEG formats are used in the fields of data storage and broadcasting.
The challenge of a new coding standard for higher image quality is to have compatibility with these existing standards. One method for keeping compatibility is an existing decoder capable of decoding a part of a bit stream coded in the new standard format. For example, a method has been suggested in which the resolution of an image is hierarchically divided into a low-resolution image area and a high-resolution image area and an existing standard is applied to the low-resolution area while a new standard is applied to the high-resolution area so as to obtain a reconstructed image (see, for example, Patent Reference 1).    Patent Reference 1: Japanese Laid-Open Patent Application No. 05-308631 Publication